From Haug & Walker's Journey to the Cross:

"Our consumerism is rooted in a lack of faith. We are worried about what others think because we are not convinced that God delights in us (Psalm 149:4). We are anxious because we do not believe God will meet our needs (Matthew 6:32). We vie for attention because we do not think God rewards what is done in secret (Matthew 6:6). We compare ourselves to others because we forget that Jesus is our righteousness (1 Corinthians 1:30). A consumer is self-seeking because he is preoccupied with building his own kingdom in order to meet his own needs. ... Jesus especially calls us to re-right our lives, to "Seek first the kingdom of God and his righteousness, and all these things will be added to you" (Matthew 6:33).

"The simple practice of self-denial ... teaches us that those who trust God to meet their needs are free to consider the needs of others. They discover this gospel paradox: As long as I'm looking to get my needs met, I will never get my needs met. But when I begin to meet the needs of others--when I begin to live for them instead of for myself--I find that God graciously takes care of my needs in the process. The grace of God turns us into  servants. Instead of demanding that we be served, we joyfully lay down our rights and seek to serve God and others."